Deformable closure for containers

ABSTRACT

A deformable closure for containers of the type having an interior lacquered shell and a sealing liner secured therein. The liner has an outer peripheral annular sealing area and an inner central non-sealing area. The lacquer applied to the shell is composed of a composition to which the liner is poorly adherent. The lacquered shell has applied thereto an adhesion promoting coating which contacts the liner in the non-sealing area and renders the liner portion adherent thereto so that the liner is strongly adherent to the shell in the non-sealing area and poorly adherent to the shell in the sealing area.

United States Patent [1 1 Brockett et al.

111 3,749,272 [451 July 31,1973

[5 1 DEFORMABLE CLOSURE FOR CONTAINERS [75] Inventors: Halford E. Broekett, Elmhurst;

Robert C. Melberg, Flossmoor, both of Ill.

[73] Assignee: Continental Can Company, Inc.,

New York, NY.

[22] Filed: May 8, 1972 [21] Appl. No.: 250,995

iillllllll I llllll Primary ExaminerDonald F. Norton Attorney-Paul Shapiro et al.

[5 7 ABSTRACT A deformable closure for containers of the type having an interior lacquered shell and a sealing liner secured therein. The liner has an outer peripheral annular sealing area and an inner central non-sealing area. The lac quer applied to the shell is composed of a composition to which the liner is poorly adherent.

The lacquered shell has applied thereto an adhesion promoting coating which contacts the liner in the non-sealing area and renders the liner portion adherent thereto so that the liner is strongly adherent to the shell in the non-sealing area and poorly adherent to the shell in the sealing area.

5 Claims, 3 Drawing Figures lli a'smszvz PATENIH] JUL 3 1 I973 1 DEFORMABLE CLOSURE FOR CONTAINERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to new and useful improvements in container closures and more particularly to deformable closures which are secured to a bottle or like container by means of a thread formed on the closure during the closing operation.

2. The Prior Art lt is well known to the art to effect top and side sealing of containers having an externally threaded neck by applying to the mouth of the neck a closure made of a permanently deformable metal such as aluminum consisting of a crown in the shell of which is secured a resilient sealing liner and an annular skirt depending from the shell having a diameter greater than that of the thread.

The closure loosely applied to the container neck is deformed by a sealing head so that a portion of the crown is pressed towards the exterior sides of the mouth portion of the threaded neck whereby portions of the sealing liner are turned inward to form a side seal. This deforming operation is referred to in the art as reforming. The skirt portion of the closure is deformed to effect interengagement thereof with the threaded portion of the neck by means of thread rollers positioned symmetrically about the container which inwardly deform the skirt between adjacent thread ribs on the container neck.

Deformable closures of the type described above have been adapted to form tamper-proof closures. In the construction of tamper-prof closures, the deformable closure forms a removable top portion which is connected to a depending ring portion by means of a series of fracturable bridge members with the retaining ring portion having its lower edge secured'to the container by being crimped under an annular flange portion on the neck of the container.

Materials which can be used to form sealing liners secured to the shells of the deformable closures are generally rubber-like resilient materials which are flowable under the pressures to which the closure is subjected to during reforming. Plastisol compositions are preferred and are widely used as sealing linersfor closures as they are easily applied materials characterized by resistance to acids, beverage, and food products and are relatively tasteless and odorless and are not affected by moisture.

A serious problem encountered in using plastisol lined deformable closure is that in an undersirable number of cases, the'mounted closure is tilted when reformed on the container neck and when this happens the lower edge of the fracturable ring portion of the closure will not come in full contact with the annular flange during sealing. This phenomenon is referred to' in the art as mis-tucking. Containers sealed with closures which are mis-tucked have an unattractive appearance and have very poor aesthetic appeal to the consumer.

The problem of mis-tucking during reforming of plastisol lined closures is believed due to the inability of the liner to move freely under the reforming pressures during the sealing operation. In reforming the closure, the portion of the linear in the sealing area is caused to flow or be extended by the sealing pressures extend during the reforming operation to create the top and side seal for the container. If the plastisol liner is completely adhered to the interior shell surface, the extrusion of the plastisol liner material is impeded and a non-uniform pressure is applied to the closure which prevents the closure from being uniformly drawn down the container neck. This non-uniform drawing of the closure causes the closure to be applied to the container neck in a tilted or cocked manner.

In US. Pat. No. 3,465,907 there is described one means for eliminating closure mis-tucking whereby the interior shell of the deformable closure is first coated with a lacquer layer to which the sealing liner is adherent. The applied lacquer layer is then coated in the area of the shell which contacts the sealing area of the liner with a coating which creates a low order of adhesion between the liner surface and the lacquer layer so that the liner is strongly adherent to the shell in the inner central non-sealing area and poorly adherent or substantially non-adherent to the shell in the outer peripheral annular sealing area. By applying the liner to the closure shell in this manner, free movement of the liner material necessary for sealing occurs, and mis-tucking of the closure during reforming is substantially reduced. A l 1 Although the problem of mis-t ucking has been greatly alleviated using deformable closures of the type disclosed in U.S. Pat. No. 3,465,907, certain disadvantages exist in their manufacture. The'primary disadvantage is that it is extremely difficult to apply a ring of low adhesion material with any great deal of accuracy to the annular peripheral sealing area of the closure shell. lnprecise application of the low adhesion coating, namely in areas outside the closure sealing area, results in closures having defective liners. I

SUMMARY OF THE INVENTION. 7

in accordance with the present invention, there is provided a deformableclosure having a resilient liner secured therein and adapted for sealing bottles and like containers wherein the interior shell of the closure is coated with a lacquer layer to which the liner is substantially non-adherent, the central, non-sealing area of the liner being adhered to the lacquered shell surface with an adhesion promoting coating material which is adherent to both the liner and the lacquered shell surface.

By coating the shell surface with a lacquer coating to which the liner is substantially non-adherent and adhering the liner to the shell with'an adhesion promoting coating material which renders the non-sealing area of the liner adherent to the shell, there is obtained a deformable closure having a liner adhered thereto wherein the annular sealing area is poorly adherent to the shell permitting free movement of the liner during the closure reforming operation. As the application of a non-adhesive ring to the annular peripheral sealing area of the closure shell is eliminated in closures ofthe present invention and since application of an adhesion promoting coating material to the non-sealing area of the shell requires substantially less precision and accuracy than is required for an application of coatings to the peripheral sealing areas of the closure shell, the problems previously encountered in the manufacture of deformable closures are eliminated.

THE DRAWINGS In order that the invention may be clearly under stood, some embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which FIG. 1 is a section view of one form of a deformable closure according to the invention.

FIG. 2 is a plan view into the open face of the lacquered closure shell before application of the liner according to the invention.

FIG. 3 is a like view with a formed liner in place.

It is to be understood that although the figures illustrate a deformable. closure of the type disclosed in U.S. Pat. No. 3,465,907, the present invention is applicable to closures which do not contain retaining ring portions and are not tamper-proof.

Referring to the drawings, FIG. 1 illustrates one form of closure cap 10 according to the invention, the closure 10 being made of permanently deformable material such as tinplate or aluminum and comprising a crown portion 11, a skirt portion 12 and a retaining ring portion 13 formed integrally with the skirt portion 12 and extending downwardly from the lower end of the skirt.

The retaining ring portion 13 of the closure 10 is secured to the lower end of the skirt portion by means of a series of fracturable bridge members 14. By securing the retaining ring portion 13 to the cap 10 in this manner, the ring may be easily severed from the cap portion when the cap is twisted relative to the retaining ring.

As illustrated in FIG. 2, the interior upper face of the cap 10 is coated with an internal lacquer layer 15. The lacquer can be of any material to which a plastisol liner will be substantially non-adherent or adhere with alow order of adhesion. An example of a suitable lacquer is the thermosetting epoxy-vinyl-urea/formaldehyde resin mixtures conventionally used in coating the interior of metal containers. Such a lacquer applied to the metal from which the closure shell is formed and baked at 370 F for l minutes at a film weight of about 2.5 mg/sq. inch provides a protective lacquer coating for the closure shell to which the plastisol liner is poorly adherent.

To the lacquared surface 15 is applied an adhesion promoting material 16 which is adherent to the lacquered surface 15 and to which the subsequently applied plastisol liner will also be adherent. The adhesion promoting coating material 16 is applied to the lacquered surface 15 in any convenient form known to the coating art. Preferably, and most conveniently, the coating material 16 is formulated having the consistency of a printing ink which can be applied to the lacquered surface by high speed printing presses normally employed in the closure art for printing indica on lacquered metal surfaces. As shown in the drawing, the adhesion promoting coating material 16 is applied to or printed on the lacquered closure shell in the form of a circular spot.

The adhesion promoting coating material 16 may be formulated from any synthetic resin composition which creates a high order of adhesion between the liner and the lacquered shell. An adhesion promoting coating material which has been found especially suitable for use in the practice of the present invention are plasticized vinyl chloride polymer compositions prepared from a mixture of (l) 30 to 50 weight percent of at least one vinyl chloride polymer resin (2) 40 to 60 weight percent of an epoxidized, unsaturated oil plasticizer and (3) to weight percent of a methacrylate polymer tackifier. These plasticized vinyl chloride polymer compositions are more completely described in U.S. Pat. No. 3,361,381, the disclosure of which is incorporated in this application by reference.

As illustrated in FIG. 3, after application of the adhesion promoting coating 16, a resilient sealing liner 17 consisting of a thick annular portion or sealing ring 18 for engagement with the container lip and a thin central non-sealing portion 19 is provided in the closure shell The sealing liner 17 can be made of any material which provides a resilient liner and which is flowable under the pressures to which the deformable closure is subjected during reforming operations. Suitable'materials from which the liner may be formed include rubber/resin blends, including blends based on neoprene, nitrile, natural, styrene-butadiene, and ethylenepropylene rubbers; vinyl resin compositions, including plastisols of vinyl chloride polymers and blends of vinyl resins, polyurethane rubbers and rubber gaskets prepared from solutions or latices and flowed and solidi fled in position in the closure shell. These materials may be modified by the addition of various additives to impart desirable properties such fillers, plasticizers, tackifiers, curing agents and antioxidants.

Plastisols are preferred as materials from which the sealing liner can be formed. Useful plastisols for the liner composition include 39 to 77 percent by weight of the plastisol of fine granules of vinyl chloride polymers such as polyvinylchloride or copolymers of vinyl chloride with up to about 20 weight percent of a copolymerizable ethylenically unsaturated monomer such as vinyl acetate, maleic anhydride, vinylidene chloride, dibutyl maleate and mixtures of such monomers, the polymer granules being suspended in 18 to 58 percent by weight of the plastisol compositionof a conventional vinyl resin plasticizer such as an alkyl phthalate such as dioctyl phthalate or an epoxidized oil such as epoxidized linseed oil, a dicarboxylic acid ester, a triaryl phosphate or a combination of plasticizers.

The plastisol may be deposited in the closure shells by various known techniques, one being the so-called flowed in technique wherein the plastisol composition in an uncured, plastic like condition is squirted from 'one or more nozzles into the closure shells which are turned upside down on a chuck rotating at high speed. Due to centrifugal force, the sealing liner material will assume the desired contour and shape. After being thus deposited or flowed in the liners are cured by a heating operation according to known procedures and using known equipment. The cured liners will permanently adhere to'the lacquered interior of the shell only in those areas to which the adhesion promoting coating has been applied;

After deposition'of the plastisol liner in the shell, the closure may be reformed on a container neck to seal the container in the conventional manner and as more particularly described in U.S. Pat. No. 3,465,907 which disclosure is incorporated in this application by reference.

The invention is further illustrated by the following example:

. EXAMPLE Deformable aluminum closures formed of a shell having an outside diameter of 1.125 inches and a depending skirt having a retaining ring attached thereto of the type illustrated in FIG 1 of the drawings were provided with a layer of an epoxy-vinylurca/formaldehyde resin lacquer over the entire inner shell surface at a film weight of 2.5 mg/sq. inch, and baked at 370 F for minutes. A spot, 0.625 in diameter, of an adhesion promoting coating material having the consistency of a printing ink was applied by a lithographic press over the lacquered surface in the center of the shell at a film weight of 2.5 mg/in as shown in H6. 2 of the drawings. The coating spot was baked at 370 C for 10 minutes. The adhesion promoting coating material had the following composition:

Component Parts by Weight Polyvinylchloride resin 33.2

Vinyl chloride/maleic 8.3 anhydride copolymer having a carboxyl content of 1.67%

Epoxidized Linseed Oil 49.8 Methylmethacrylatelnbutyl- 8.3 methacrylatc copolymer Stabilizer (Calcium-Zinc salt 0.4

Component Parts by Weight Polyvinylchloride resin 100 Epoxidized Soybean Oil 5 Dioctyl Phthalate 60 Calcium-Zinc Stabilizer l Wax 2 The plastisol liner was substantially adherent to the closure shell in the central, non-sealing area of the shell to which the adhesion promoting coating spot had been applied and substantially non-adherent to the sealing area of the lacquered shell.

The plastisol lined closures were reformed on screw threaded 8 and I0 02 bottles in the manner disclosed in US. Pat. No. 3,465,907 using conventional closing machinesat a rate of 250 bottles per minute. After application of the closures, the bottles are examined for mis-tucks. The number of mistucks per 360 bottles sealed in this manner was 1.

By way of contrast, the number of mis-tucks generally obtained with closures of the type disclosed in US. No. 3,465,907 normally ranges about 8 to 10.

What is claimed is: l. A closure for a container comprising a shell adapted for mechanical engagement with the container and extending over the container mouth, the shell having a lacquer layer thereon and containing a resilient sealing liner which is poorly adherent to the lacquer layer,

the liner comprising an outer peripheral annular sealing area and an inner central non-sealing area,

the lacquer layer having applied thereto an adhesion promoting coating which contacts the inner nonsealing area of the liner and which renders the nonsealing area of the liner strongly adherent to the lacquer layer, so that the liner is strongly adherent to the lacquered surface of the shell in the inner non-sealing area of the liner and poorly adherent to the lacquered surface of the shell in the outer peripheral annular sealing area of the liner.

2. The closure of claim 1 made from permanently deformable metal material.

3. The closure of claim 1 wherein the sealing liner is formed from a plastisol composition.

4. The closure of claim 1 wherein the adhesion promoting coating is comprised of a plasticized vinyl chloride polymer.

5. The closure of claim 1 wherein the adhesion promoting coating is applied as a spot to the central portion of the shell. 

2. The closure of claim 1 made from permanently deformable metal material.
 3. The closure of claim 1 wherein the sealing liner is formed from a plastisol composition.
 4. The closure of claim 1 wherein the adhesion promoting coating is comprised of a plasticized vinyl chloride polymer.
 5. The closure of claim 1 wherein the adhesion promoting coating is applied as a spot to the central portion of the shell. 